Filter and absorbing dyes for use in photographic emulsions



Oct. 18, 1960 J. H. VAN CAMPEN FILTER AND ABSORBING DYES FOR USE INPHOTOGRAPHIC EMULSIONS Filed Jan. '7, 1958 2 Sheets-Sheet 1 COUPLER FORCYAN IMAGE RED SENS/T IVE EMULSION OOUPL ER FOR [WAGE/VT! IMAGE GREEN 3E NSITI VE EMULSION Ii 9 1 COUPLER FOR YELLOW IMAGE BLUE-8EN8ITIVEEMULSION lo ;suPPo RT l I 152 .2 100 l;

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OPTICAL DENSITY OPTICAL DENSITY Oct. 18, 1960 J. H. VAN CAMPEN 2,956,379

FILTER AND ABSORBING was FOR uss m PHOTOGRAPHIC smszons Filed Jan. 7,1958 2 Sheets-Sheet 2 500 20 4O 60 60 600 20 40 60 80 700 WAVELENGTH INMILLIMICRONS 400 20 40 6O 80 500 20 4O 60 80 600 20 4O 60 80 700WAVELENGTH IN MILLIMICRONS Johnflvancanyen Fig.4 1V2 TQR. 1

ATTORNEYS FHII'ER AND ABSOFNG DYES FOR USE IN PHOTOGRAPHIC EMULSIONSJohn H. Van Campen, Rochester, N.Y., assignor to Eastman Kodak Company,Rochester, N.Y., a corporation of New Jersey Filed Jan. 7, 1958, Ser.No. 707,511

14 Claims. (CI. 96-74) This invention relates to photographic emulsionsand photographic elements comprising such emulsions, and, moreparticularly, to such photographic products containing certainlight-absorbing agents.

In certain photographic processes, and in particular those concerningcolor photography or reproduction of natural colors, thelight-scattering caused by the silver halide grains creates considerablediifculty. For example, light which has been scattered by a given silverhalide grain will travel until it strikes another silver halide grainwhere it is absorbed, thus making this latter silver halide graindevelopable. Of course, since this silver halide grain may not have beenoriginally exposed, but received only secondary radiation, itsdevelopment is not desired. In the past, it has been proposed toovercome this scattering effect by incorporating various dyes, otherthan optical or spectral sensitizing dyes, in the emulsions. While thispractice might overcome to some extent the adverse effects of thelight-scattering caused by the silver halide grains, other newdifficulties are sometimes introduced. In some cases, theselight-absorbing dyes leave residual stain, particularly Where the silverhalide emulsions have been coated upon a fibrous or paper base. Thisdifficulty is particularly pronounced when continuous processing isused, which means that substantial quantities of sensitized materialsare treated in the same photographic developer without removingsolubilized materials which have a tendency to concentrate in thephotographic developer. Of course, if the solubilized materials,including the light-absorbing dyes, which concentrate in the developer,can be removed during subsequent washing operations, no great harm isdone. Frequently, however, these materials are not removed duringsubsequent operations so that they remain in the finished material asresidual stain. Sometimes certain light-absorbing dyes give undesirableincreases in background density, and even more serious in certain cases,a substantial loss in speed results due to the desensitizing effect ofthe dyes. I

I have now found that a particular group of a20- naphthalene dyescontaining from 3 to 4 sulfo groups can advantageously be employed inphotographic silver halide emulsions, and, in particular,green-sensitized silver halide emulsions, for the purpose of overcomingthe difficulties mentioned above. The advantages of my inventionare-particularly outstanding in continuous processing of color materialscomprising a fibrous or paper base.

It is, therefore, an object of my invention to provide photographicsilver halide emulsions containing lightabsorbing azonaphthalene dyescontaining from 3'to 4 sulfo groups. Another object is to providephotographic silver halide emulsions optically or spectrally sensitizedto the green region of the spectrum containing said amnaphthalene dyes.A further object is to provide photographic elements comprising saidphotographic silver halide emulsions. Still another object is to providephotographic elements for subtractive color photography comprising aplurality of photographic silver halide emulsions, the sensitivity ofwhich lies in different regions of the spectrum. Still another object isto provide photographic elements for color photography comprising apaper support which contains little or no residual stain after thephotographic silver halide emulsions coated may tend to wanderthroughout all layers coated on the support, yet no seriousdesensitizing or sensitizing effects have been observed.

The azonaphthalene dyes useful in practicing my invention contain from 3to 4 sulfo groups and have their maximum absorption in the region of thespectrum to which the photographic silver halide emulsion, to which theyare added, is sensitive (which is generally the green region of thespectrum). Because of the sulfo substituent attached to the naphthalenerings, these dyes generally have a high degree of solubility in water.

By sulfo groups I mean the sulfonic acid group itself or water-solublesalts thereof, including alkali metal salts (e.g., sodium, potassium,etc.), ammonium salts (i.e., ammonium or organic ammonium, such astriethylammonium, pyridinium, tniethanolammonium, etc.), etc.

Typical of the dyes which can be used in my invention are thoserepresented by the following general formula:

wherein R and R each represents a bi-nuclear aromatic group of thenaphthalene series, said aromatic group containing at least one sulfosubstituent, the total number of said sulfo substituents in the dyesrepresented by Formula I being from 3 to 4. A group of dyes embraced byFormula I above which can be used in my invention comprise the dyesrepresented by the following general formula:

II. (S 0 3M) d-l wherein R R R and R each represents a hydrogen atom, analkyl group (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobu-tyl,etc., especially an alkyl group containing from 1 to 4 carbon atoms), analkoxyl group (e.g., methoxyl, ethoxyl, etc.), a hydroxyl group, anamino group (e.g., amino, monoalkylamino, such as methylann'no,ethylamino, etc., dialkylamino, such as dimethylamino, diethylanrino,etc., acylamino, such as acetamido, propionamido, benzamido, etc.), anacyl group (e.g., acetyl, propionyl, etc.), a cyano group, etc., d, m, nand q each represents a positive integer of from 1 to 3, the sum of d,m, n and q being from 7 to 8, and M represents a hydrogen atom, analkali metal atom ,or an ammonium radical as defined above with respectto the sulfo groups which must be present in my light-absorbing dyes.Especially useful dyes embraced by Formula 11 above are those dyeswherein R or R represents a hydroxyl group.

Specific dyes which can be employed in practicing my invention, whichare embraced by the above general Formula I, include the following:

SOaNa OH SOaNa SOaNa The above dyes can be prepared according to methodswhich have been previously described in the prior art. Dye 3 above isWell-known as Schultz 213 and is sold commercially under such tradenamesas Brilliant Scarlet 3R or Ponceau 4R Cone. It has the Color Index No.185. Dye 4 above is well-known as Schultz 212 Dye.

The method of incorporating the azonaphthalene dyes of my invention inphotographic silver halide emulsions is quite simple and can be effectedmerely by adding the solid dyes to the emulsions, although it isgenerally preferable to dissolve the dyes in an inert solvent, such aswater, and disperse the dyes in the emulsions in the form of theirsolutions. Where the dye does not have sufficient solubility in water toperform the desired degree of light absorption, its solubility can beincreased by adding a small amount of an organic solvent, such aspyridine, to the aqueous solvent. Alternatively, the dyes can be firstdissolved in an organic solvent and then added to water prior toaddition to the photographic emulsions. Since the dyes of my inventionare generally characterized by a high degree of solubility in Water, itis usually not necessary to resort to any particular technique in orderto disperse the dyes uniformly throughout the emulsions. In general, Iprefer to add the dyes directly to the finished, washed emulsions in theform of their aqueous (neutral) solutions. If desired, the emulsions canbe digested for a short time before coating.

The quantity of azonaphthalene dye employed in my invention can bevaried, depending upon the particular emulsion used, the concentrationof silver halide, effects desired, etc. In general, I have found thatfrom about 0.5 to 5.0 mg. of dye/ft. of coated emulsion is quiteadequate for the purposes of my invention. Based on the quantity ofsilver halide in the emulsion, I have found that from about 0.5 to aboutgrams of dye per gram mole of silver can be employed, although larger orsmaller amounts of dye can be used, depending upon the particularconditions, some of which are mentioned above.

The photographic silver halide emulsions employed in my invention can beoptically sensitized or unsensitized. The usual optical sensitizing dyescan be used, such as the cyanines, merocyanines, complex (tninuclear)cyanines, complex (trinuclear) merocyanines, styryls, hemicyanines, etc.These dyes can contain the usual basic nuclei, such as tbiazole,benzothiazole, naphthothiazole, benzoxazole, naphthoxazole,benzoselenazole, naphthoselenazole, quinoline, etc., or in the case ofthe merocyanine dyes, such nuclei as rhodanine, 2-thiohydantoin,oxazoledione, pyrazolone, etc. Such dyes, for example, are described inBrooker US. Patent 2,185,182, dated January 2, 1940; Brooker US. Patent2,241,237, dated May 6, 1941; Carroll US. Patent 2,635,961, dated April21, 1953; Carroll U.S. Patent 2,652,330, dated September 15, 1953;Heseltine and Brooker US. Patent 2,666,761, dated January 19, 1954;Carroll and Jones US. Patent 2,704,715, dated March 22, 1955; etc. Ingeneral, the particular azonaphthalene dye used should have its maximumabsorption in the same spectral region to which the sensitizing dyesensitizes the emulsion.

My invention is primarily directed to the ordinarily employed silverhalide developing-out emulsions, e.g., gelatino-silver-chloride,-chlorobrornide, -chloroiodide, -chlorobromiodide, -bromide and-bromiodide developingout emulsions. Particularly useful results havebeen obtained with gelatino silver chloro bromide emulsions which areuseful in preparing subtractive color reproductions on fibrous or papersupports. Emulsions which form the latent image mostly inside the silverhalide grains, such :as the emulsions set forth in Knott and Stevens US.Patent 2,456,956, dated December 211, 1948, can also be employed inpracticing my invention.

While my invention is particularly directed to the ordinarily employedgelatino-silver-halide emulsions, carriers other than gelatin, e.g., aresinous substance, such as polyvinyl alcohol, or cellulosic material,such as bydrolyzed cellulose acetate, which has no deteriorating elfectupon the light-sensitive silver salt materials, can be employed.

The emulsions prepared in accordance with my invention can be coated inthe usual manner upon any suitable support, e.g., glass, cellulosenitrate film, cellulose acetate film, polyvinyl acetal resin film,polycarbonate film, polystyrene film, polyester film, metal, etc.,although I have found that the advantages of my invention areparticularly outstanding when the support is paper or some other fibrousmaterial which is more likely to absorb stain than hydrophobic filmmaterials. Since the emulsions themselves also tend to absorb solubledeveloper components and decomposition products, it is to be understoodthat the advantages of my invention also extend to film materials orother hydrophobic supports, although the results are not as outstandingin these instances.

Photographic silver halide emulsions, such as those listed above, canalso contain such addenda as chemical sensitizers, e.g., sulfursensitizers (e.g., allyl thiocarbarnide, thiourea, allylisothiocyanate,cystine, etc.), various gold compounds (e.g., potassium chloroaurate,auric trichloride, etc.) (see Baldsiefen US. Patent 2,540,085, datedFebruary 6, 1951; Damschroder US. Patent 2,597,- 856, dated May 27,1952; and Yutzy and Leermakers U.S. Patent 2,597,915, dated May 27,1952), various palladium compounds, such as palladium chloride(Baldsiefen et al. US. Patent 2,540,086, dated February 6, 1951),potassium chloropalladate (Stauffer and Smith US. Patent 2,598,079,dated May 27, 1952), etc., or mixtures of such sensitizers;antifoggants, such as am monium chloroplatinate (Trivelli and Smith U.S.Patent 2,566,245, dated August 28, 1951), ammonium chloroplatinite(Trivelli and Smith U.S. Patent 2,566,263, dated August 28, 1951),benzotriazole, nitrobenzimidazole, 5- nitroindazole, benzidine,mercaptans, etc. (see Mees, The Theory of the Photographic Process,Macmillian Pub., 1942, page 460), or mixtures thereof; hardeners, suchas formaldehyde or chrome alum (Miller U.S. Patent 1,763,- 533, datedJune 10, 1930), glyoxal (Brunken US. Patent 1,870,354, dated August 9,1932), dibromacrolein (Bloch et al. British Patent 406,750, acceptedMarch 8, 1934), etc.; color couplers, such as those described inSalminen and Weissberger U.S. Patent 2,423,730, dated July 8, 1947,Spence and Carroll US. Patent 2,640,776, dated June 2, 1953, etc.; ormixtures of such addenda. Dispersing agents for color couplers, such asthose set forth in Jelley and Vittum US. Patent 2,322,027, dated June15, 1943 and Mannes and Godowsky U.S. Patent 2,304,- 940, dated December15, 1942, can also be employed in the above-described emulsions.

The following example will serve to illustrate the beneficial effect ofthe azonaphthalene dyes of my invention as compared with aclosely-related azo dye which has been used previously for the samepurpose. This example illustrates that there is much less speed loss inthe green region of the spectrum using the dyes of my invention thanresults when a closely-related dye is used for light-absorbing purposes.

EXAMPLE 1 To different portions of the same batch of photographicgelatinosilver-chlorobromide emulsion (green sensitized) containing acoupler for the magenta image, such as one of the pyrazolone couplersdescribed in Loria et a1. U.S. Patent 2,600,788, dated June 17, 1952(e.g., 3-{3-[(2", 4"-di-tert. amylphenoxy) acetamido]benzamido}-1-(2',4', 6-trichlorophenyl) 5-pyrazolone) was added anazonaphthalene dye, as identified in Table I (Dye 3), the amounts usedbeing given as mg./ft. of the coated emulsions. The emulsions were thendigested for a short time and coated on a paper support, chill set anddried. A second series of photographic gelatino-silver-chlorobromideemulsions was treated with a difierent light-absorbing dye, Azorhodine2G, in the amounts given in the table (mg/ft?) and the emulsionsdigested for a short time, coated on a paper support, chill set anddried. Each of the series of coated emulsions was then exposed in anintensity scale sensitometer using 3000 K.-500 watt illumination from aprojection incandescent lamp. The exposed emulsions were then processedin a developer having the following composition:

4-arm'n0-N-ethy1-N-(B-methanesulfonamidoethyl)m toluidine sesquisulfatemonohydrate.

The developed coatings were then immersed in a stop bath for about 2minutes. The stop bath had the following composition:

liter 1.0

Water Glacial acetic acid cc 17.0 Sodium sulfite, anhydrous grams 20.0

The coatings were then fixed for 2 minutes in a bath having thefollowing composition:

Water liter 1.0 Sodium thiosulfate grams 223 Sodium bisulfite do 12.0Sodium acetate, anhydrous do 14.0 Sodium citrate do.. 1.7 Boric acid do5.0 Potassium alum, granular do. 24.0

The coatings were then washed in running water at about 73 to 77 F. for2 minutes. The paper coatings were then treated for 4 minutes at 73 to77 F. in a bleach bath having the following composition:

Water liter 1.0 Sodium nitrate grams 45.0 Potassium ferricyanide do 22.5Potassium bromide do 8.2 Boric acid dn 7.5 Borax do 0.97

The paper coatings were then washed in running water at 73 to 77 F. for2 minutes and then fixed for 2 minutes in a hardener-fixing bath havingthe following composition:

The paper coatings were then washed in running water at 73 to 77 F. for8 minutes and then treated for 3 minutes in a hardening bath at 73 to 77F., the bath having the following composition:

Water liter 1.0 Sodium hexametaphosphate (Calgon) grams 0.75 Sodiumcarbonate monohydrate do 8.8 Formaldehyde (37% by weight) ccs 25.5

The paper coatings were then washed for 2 minutes in running water andtreated for 3 minutes in a buffer bath having the following composition:

Water liter 1.0 Citric acid grams 30.0 Borax do 20.4

The prints were then allowed to dry in the air or in a conventionaldrier.

The speeds of the coatings obtained above were then read on a curvetracing reflection densitometer which read the curves of monochromaticdensity as a function of exposure. A Perkin-Elmer Monochromator, Model83, equipped to emit 596 mu radiation, was used as a light source. Thespeed figures are given in the following table in terms of log E units.The control coating had a green density in the shoulder region of thecurve of about 1.40, in the toe region a density of about 0.06 and freshmagenta stain of about 0.10. The coatings containing the light-absorbingdyes had density values approximately the same as the control coating,insofar as the shoulder and toe regions of the curve and stain wereconcerned. Of course, it is to be understood that these figures wereobtained from a single run and that the stain level had no opportunityto build up as would occur in a continuous process.

Table I Fresh Speed Coating Addenda Conc.

( s-l t) Green A log E My invention can be further illustrated byreference to the accompanying drawings, in which:

Figure 1 is a diagrammatic, cross-sectional view of a multilayer colorelement which can be advantageously processed according to my invention,

Figure 2 is a reproduction of a set of reflectance curves showing theadvantages of using the light-absorbing dyes of my invention over astructurally-related dye,

Figure 3 is a reproduction of the spectrophotometric curve of pureSchultz 213 Dye, and

Figure 4 is a reproduction of the spectrophotometric curve of a dye,Azorhodine 2G, which is structurally related to the dyes of the instantinvention.

In Figure 1, there is shown in cross-sectional view, a photographiccolor element of the type which can be advantageously employed in myinvention. The element comprises a support 10, which can be composed ofany conventional material, such as those listed above, and ablue-sensitive silver halide emulsion layer 111 coated on top of thissupport. The blue-sensitive emulsion can contain a coupler orcolor-forming compound which reacts with the oxidation products of thecolor developer to produce a yellow image. Coated on top of thebluesensitive layer is a green-sensitive silver halide emulsion layer12, which can contain a coupler or color-forming compound capable ofcoupling with the oxidation products of the color developer to produce amagenta image. The element shown has an outermost red-sensitive silverhalide emulsion layer 13, which is coated on top of the green-sensitiveemulsion. This red-sensitive emulsion can contain a coupler orcolor-forming compound capable of coupling with the oxidation productsof a color developer to produce a cyan image. The photographic supportillustrated in Figure 1 can, if desired, contain interlayers (notshown), such as gelatin interlayers, filter layers, etc.

As indicated above, the advantages of my invention are particularlyoutstanding in the continuous processing of multilayer color elements,which involves large quantities of sensitized stock and prolonged use ofthe same developing baths. Under such rigid conditions, it is obviousthat the quantity of soluble materials in the sensitized stock willapproach an equilibrium with the soluble materials in the developingbaths. Consequently, it is to be expected that the quality of theprocessed materials will fall off rapidly if some control is notexercised over the processing. 1 have found that the dyes of myinvention are markedly superior to dyes which have been customarily usedin the prior art in the green-sensitive layers of color elements,particularly from the standpoint of less desensitization and stain (bothwith respect to the emulsions themselves and the paper supports whichare frequently used for print materials). The advantages of my inventionwith respect to stain level are illustrated in the following example.

EXAMPLE 2 Part (a).A photographic 3-layer material similar to the typeillustrated in Figure l was continuously processed until the amount oflight-absorbing dye in the color developer reached a maximum. Themultilayer element comprised a support having coated thereon an ordinarygelatino-silver-chlorobromide emulsion which was bluesensitive andcontained a coupler for the yellow image of the type described inMcCrossen et al. US. application Serial No. 575,099, filed March 30,1956 (now US. Patent 2,875,057, issued February 24, 1959). Thebluesensitive layer also contained conventional emulsion addenda, suchas an anti-stain agent (e.g. 2-n-octadecyl-5- (Z-sulfo-tert.butyDhydroquinone potassium salt, etc.), etc. Coated over theblue-sensitive layer was an ordinary gelatin interlayer. Over thisgelatin interlayer was coated an ordinary gelatino-silver-chlorobromideemulsion which was green-sensitive and contained a coupler for themagenta image, such as one of the couplers described in Loria et al. US.Patent 2,600,788, dated June 17, 1952. The coupler was disposed in aconventional coupler solvent, such as tricresylphosphate. Thegreen-sensitive emulsion layer also contained an anti-stain agent, suchas dioctylhydroquinone. The green-sensitive emulsion layer alsocontained a quantity of Schultz 213 Dye suflicient to give a coverage of3.0 mg./ft. of coating.

Over the green-sensitive layer was coated an ordinary gelatin layercontaining an ultra-violet absorbing compound, such as one of thecompounds described in Sawdey US. Patent 2,739,888, dated March 27,1956. Also, the gelatin filter layer contained dioctylhydroquinonedispersed in a solvent, such as tricresylphosphate. Over the gelatinfilter layer was coated an ordinary gelatinosilver-chlorobromideemulsion which was red-sensitive. This red-sensitive emulsion containeda coupler for the cyan image, such as one of the couplers described inFierke US. Patent No. 2,801,171, dated July 30, 1957, the couplers beingdispersed in a conventional solvent, such as dibutyl phthalate. Thered-sensitive emulsion also contained an anti-stain agent, such asdioctylhydroquinone, and a red-light absorbing dye of the type describedin Saunders and Wilson US. application Serial No. 541,059, filed October17, 1955 (now US. Patent 2,865,752, issued December 23, 1958). Over theredsensitive layer was coated an ordinary gelatin protective layer.

The above element was exposed in the customary man ner to a subject andthe exposed coatings processed in the same processing baths describedabove in Example 1. A total of 1800 square feet of coating was processedover a period of 24 hours. The developer composition was then analyzedand the decomposition products contained therein measured by means of aspectrometer using 302 m radiation. The results of the analysis aregiven in Table II below, where the coating is identified as element A.

Part (b).A second series of coatings was run in the manner describedabove for element A, except that the green-sensitive layer of the colorelement contained 3.0 mg./ft. of Azorhodine 2G light-absorbing dye inplace of the Schultz 213 Dye used in Part (a). After a total of 2250square feet of coating had been processed over a period of 30 hours, theconcentration of the Azorhodine 2G in the color developer was at amaximum. The manner of processing the coating was exactly the same asthat described in Example 1 above. The developer composition was thenanalyzed as under Part (a) above. The element used under Part ([7) isidentified as element B in the table. The composition of the seasoneddevelopers was as follows:

The specific gravity of the developer composition after seasoning theelement A was 1.031 against 1.033 for element B. The pH of the seasoneddeveloper for element A was 9.90 against 9.98 for element B.

The residual stain in the coatings obtained in Example 2 above wasdetermined both for the emulsion side of the coatings and for the paperbase. In Figure 2 of the accompanying drawings are shown the resultsobtained. The percentage reflectance is plotted as a function of thewavelength of incident light upon the paper base and the emulsions. InFigure 2, curve A represents paper base of element B. It is quiteapparentthat there is considerable stain present in element B ascomparedwith element A, particularly in the green region' In Figure 2,curve C represents the reflectance of the emulsion side of element A,while curve D (dotted line) represents the reflectance of the emulsionside of element B.' Again, it is evident that element B has considerableresidual stain as compared with element A.

In the accompanying drawings, Figure 3 is a reproduction of thespectrophotometric curve of pure Schultz 213 Dye, the density of the dyebeing plotted as a function of the wavelength.

In Figure 4, there is shown a reproduction of the spectrophotometriccurve of Azorhodine 2G Dye, the density being plotted as a function ofthe wavelength.

Azorhodine 2G Dye has the Color Index No. 31 and can be preparedaccording to conventional techniques. Dye 1 above was prepared in thesame manner as Schultz VII-226, except that diazotized2-naphthylamine-6,8-disulfonic acid was coupled with an equimolar amountof 1,8-naphthosultone-3,6-disulfonic acid in alkaline solution (insteadof with salicylic acid as for Schultz VII226). In like manner, Dye 2above was prepared, except that 1 mole of 2-naphthol-8-sulfonic acid wasused in place of the salicylic acid used to prepare Schultz VII-226.

The term sulfo as used in the foregoing specification and in thefollowing claims is intended to include the free sulfonic acid group, aswell as water-soluble salts of this group, such as sodium, potassium,ammonium, organic ammonium (e.g., pyridiniurn, triethylammonium, tri-'ethanolammonium, etc.), etc.

Azorhodine 2G, used in Examples 1 and 2 above, can

be represented by the following formula:

I Naoas I claim:

SOaNa wherein R R R and R each represents a member selected from thegroup consisting of a hydrogen atom and a hydroxyl group, d, m, n and qeach represents a positive integer of from 1 to 3, the sum of d, m, nand q being from 7 to 8, and M represents a member selected h'om thegroup consisting of a hydrogen atom, an alkali metal atom, and anammonium radical, said azo dye having its maximum absorption in thegreen-light region of the spectrum.

2. A photographic gelatino-silver-h alide emulsion optically sensitizedto the green-light region of the spectrum containing (1) a color-formingcompound capable of coupling with the oxidation products of a colordeveloper to provide a magenta image and (2) from about 0.5 to 10 gramsper mole of silver halide of an azo dye selected from those representedby the following general formula:

R Rs

wherein R R R and R each represents a member selected from the groupconsisting of a hydrogen atom and a hydroxyl group, d, m, n and q eachrepresents a positive integer of from 1 to 3, the sum of d, m, n and qbeing from 7 to 8, and M represents a member selected from the groupconsisting of a hydrogen atom, an alkali l l f N: L NBO3S Naoss SOaNa 4.A green-sensitized photographic silver halide emulsion containing fromabout 0.5 to 10 grams per mole of silver halide of the dye representedby the following formula:

SOaNa I f NaOzS NaOaS- 5. A green-sensitized photographic silver halideemulsion containing from about 0.5 to 10 grams per mole of silver halideof the dye represented by the following formula:

6. A green-sensitized photographic silver halide emulsion containingfrom about 0.5 to 10 grams per mole of silver halide of the dyerepresented by the following formula:

SOaNa on SOaNa 7. A photographic element for subtractive colorphotography comprising a support having coated thereon a plurality ofsilver halide emulsion layers, one of which is sensitive to the blueregion of the spectrum and contains a color-forming compound capable ofcoupling with the oxidation products of a color developer to produce ayellow image, one of which is sensitive to the red region of thespectrum and contains a color-forming compound capable of coupling withthe oxidation products of a color developer to produce a cyan image andone of which is sensitive to the green region of the spec trum andcontains (1) a color-forming compound capable of coupling with theoxidation products of a color developer to produce a magenta image and(2) from SOaNa 11 about 0.5 to 10 grams per mole of silver halide of awater-soluble azo dye selected from those represented by the followinggeneral formula:

wherein R R R and R each represents a member;

selected from the group consisting of a hydrogen atom and a hydroxylgroup, d, m, n and q, each represents a positive integer of from 1 to 3,the sum of d, m, n and q being from 7 to 8, and M represents a memberselected from the group consisting of a hydrogen atom, an alkali metalatom, and an ammonium radical, said azo dye haviug its maximumabsorptionin the green-light region of the spectrum.

8. A photographic element according to claim 7 wherein the support ispaper and the silver halide emulsion layer closest to the paper support'is a blue-sensitive silver halide emulsion layer, the silver halideemulsion layer farthest from the paper support is a red-sensitive silverhalide emulsion layer and the green-sensitive silver halide emulsionlayer lies between the red-sensitive silver halide emulsion layer andthe blue-sensitive silver halide emulsion layer.

9. A photographic gelatino-silver-chlorobromide emulsion opticallysensitized to the green-light region of the spectrum containing fromabout 0.5 to grams per mole of silver chlorobromide of a water-solubleazo dye selected from those represented by the following generalformula:

wherein R R R and R each represents a member, selected from the groupconsisting of a hydrogen atom and a hydroxyl group, d, m, n and q eachrepresents a positive integer of from 1 to 3, the sum of d, m, n and qbeing from 7 to 8, and M represents a member selected from the groupconsisting of a hydrogen atom, an alkali metal atom, and an ammoniumradical, said azo dye having its maximum absorption in the green-lightregion of the spectrum.

10. A photographic gelatino silver chlorobromide emulsion opticallysensitized to the green-light region of the spectrum containing (1) acolor-forming compound capable of coupling with the oxidation productsof a color developer to provide a magenta image and (2) from about 0.5to 10 grams per mole of silver chlorobromide of an azo dye selected fromthose represented by the following general formula:

wherein R R R and R each represents a member selected from the groupconsisting of a hydrogen atom and a hydroxyl group, d, m, n and q eachrepresents a positive integer of from 1 to 3, the sum of d, m, n. and qbeing from 7 to 8, and M represents a member selected from the groupconsisting of a hydrogen atom, an alkali metal atom, andan ammo-nitunradical, said azo dye having; its maximum absorption in the greenlightregion of the spectrum.

11. A photographic silver halide developing-out emulsion opticallysensitized to the green-light region of the spectrum containing (1) acolor-forming compound capable of coupling with the oxidation productsof a color developer to provide a magenta image, and (2) from about 0.5to 10 grams per mole of silver halide of an azo dye represented by thefollowing formula:

SOaNa O''SO2 NaO S NaOgS SOaNa 12. A photographic silver halidedeveloping-out emulsion optically sensitized to the green-light regionof the spectrum containing (1) a color-forming compound capable ofcoupling with the oxidation products of a color developer to provide amagenta image, and (2) from about 0.5 to 10 grams per mole of silverhalide of an azo. dye represented by the following formula:

SOaNa $11 13. A photographic silver halide developing-out emulsionoptically sensitized to the green-light region of the spectrumcontaining (1) a color-forming compound capable of coupling with theoxidation products of a color developer to provide a magenta image, and(2) from about 0.5 to 10 grams per mole of silver halide of an azo dyerepresented by the following formula:

SOsNa.

(1)11 SIOBNa NaOsS- References Cited in the file of this patent UNITEDSTATES PATENTS S OaNa 2,304,884 Carroll Dec. 15, 1942 2,428,054 Vittumet a1. Sept. 30, 1947 2,629,658 Sprung Feb. 24, 1953

1. A PHOTOGRAPHIC GELATINO-SILVER-HALIDE EMULSION OPTICALLY SENSTITIZEDTO THE GREEN-LIGHT REGION OF THE SPECTRUM CONTAINING FROM ABOUT 0.5 TO10 GRAMS PER MOLE OF SILVER HALIDE OF A WATER-SOLUBLE AZO DYE SELECTEDFROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: